It is known in the art to provide a bearing assembly for rotating a shaft of an engine, such as for example a crankshaft main bearing assembly, a camshaft bearing assembly, and a balancer shaft bearing assembly.
Such prior art bearing assemblies may use a bearing structure in which a half bearing part of the bearing assembly is formed as an integral part of the engine component used to support the bearing assembly such as, for example, a cylinder block of the engine in the case of a crankshaft main bearing assembly or balancer shaft assembly and a cylinder head in the case of a camshaft bearing assembly. U.S. Pat. Nos. 4,612,885 and 8,281,762 show example prior art bearing assemblies.
The bearing assemblies may include a bearing cap which is fastened to the half bearing part to form in combination a rotatable support for the respective shaft. With such an arrangement the bore of each bearing assembly is machined in-situ on the engine component and then the end cap has to be removed to fit the shaft and is then refastened to the half bearing part on the engine component for use.
Such a manufacturing arrangement is complex, time consuming and requires the engine component to include intricate shapes and forms to provide the half bearings. A further problem with such an arrangement is that, due to the thermally conductive nature of such a bearing assembly, the majority of the heat transferred to oil used to lubricate the bearing assembly is lost by conduction into the very large mass constituted by the engine component. For example, in the case of a main bearing assembly, a large portion of the heat generated is lost by way of conduction to the cylinder block.
Following a start-up from cold, that is an engine start-up where the temperature of the engine is originally close to ambient temperature, significant friction losses are produced due to the lubricating oil being below an optimum operating temperature. These losses increase fuel usage during the initial warm-up period and, in addition, increase wear if the oil is below a minimum temperature at which additives in the oil become fully activated. In an effort to reduce these losses it has been proposed to insulate an oil feed passage of the engine so as to reduce the loss of heat from the oil, thereby speeding up the oil heating process and reducing fuel usage. While such an approach produces a significant reduction in oil warm-up time, the heat lost from oil within a rotating shaft bearing of such an engine is not reduced.
As such in one approach, a bearing block assembly in an engine is provided. The bearing block assembly comprises at least one bearing block to rotatably support an oil lubricated shaft and fastening apparatus to attach the at least one bearing block to a flat mounting surface on a large engine component and a thermal barrier positioned between the shaft and the flat mounting surface and configured to reduce the loss of heat to the large engine component from oil used to lubricate the shaft. In this way, heat loss from oil used to lubricate a rotatable shaft bearing assembly of an engine is reduced. Additionally, the aforementioned engine bearing assembly is simple in construction, thereby reducing the cost and complexity of manufacture of the engine component to which it is fastened.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.
The figures are diagrammatic in nature.